Wrapping paper for the insulation of electric cables



Patented June 2, 1931 UNITED STATES PATENT {OFFICE CARL AUGUST HAANEN, 0F OOLOGNE-MULHEIM, D HANS OF COLOGNE, GER- MANY, ASSIGNORS '1'0 FELTEN' AN'D GUILLEAUME GARLSWEBK AC'I'IEN' GESELL- SCHAIT, OI COLOGNE-MULBEIM, GERMANY WRAPPING FOR THE INSULATION 0F CABLES I No Drawing. Application filed July 7, 1925, Serial No. 42,104, and in Germany December 27, 1024.

T he insulation of high-tension cables consists of cellulose and impregnating compound. The cellulose is used in the form of unloaded and unsized pa er. The cable papers used hitherto, whet er smoothed on the calender or. not, have a densit of from 0.60 to 0.87, the term density square metre in grams and the calculated volume of 'a square metre of pulp in cubic metres.

It has now been found that, when using the same quantity of impregnatin compound, the resistance to puncture 0 hightension cables increases, if by rolling or pressing the paper the volume proportion of cellulose to impregnating compound is raised to a certain favourable point. When the ressure applied exceeds a certain amount, t e cellulosefibres are so weakened that the resistance to tearing of the paper is inadmissibly reduced and it can no longer be wrapped on.

The present invention relates to a new method of treatin cable papers, which is to be carried out be ore the papers reach the wrapping machine, the method being based on the recognition of the fact that by it the resistance to puncture of the cable insulation is increased.

According to the invention the resistance signifying the quotient; derived from the dry weight per The treatment by rolling under pressure or by other pressure applying means may be carried out after thepaper has been im regnated with a suitable impregnating me mm, for instance parafiin, cable impregnating compounds or the like. By rolling underpressure or by other pressure applying means the paper is given .a smooth sur ace, which ensures the separate paper layers of the cable insulation lying particularly closely on one another. This latter point is also of great importance in obtaining high resistance to puncture.

What we claim is A method of increasing the resistance to puncture of wrapping paper for insulating electric cables which consists in subjecting the paper to a pressure which increases the density of the paper above .90 and still retains the necessary tensile strength for wrapping the conductor.

In testimony whereof we have signed our names to this specification.

' CARL AUGUST HAANEN. HANS MEURER- to puncture of the cable paper .is increased by the density of the paper being increased by rolling under great pressure or by other pressure applying means, but no more than the retention of the necessary tensile strength for wrapping the conductors will allow.

It has been found that the pressures to be applied must be so great. that the thickness of the paper is reduced at least by 15% of its original thickness. The pressureof the rollers can be raised to such an extent that the thickness of the paper will be reduced to about and more. Such rolling or ressmg pressures correspond to increases 0 densit of irom 0.90 to 1.30 and more.

11 papers treated in this manner it has been found that in spite of the greater density of the paper the absorbent property is not only retained but is in mos cases even increased. 

